1. Field of the Invention
The present invention relates to an air-mixing type air conditioning apparatus for a vehicle, which controls a temperature of blown-air by adjusting an air-amount ratio of cool air and warm air, and particularly relates to a mechanism for securing the maximum cooling capacity in an air conditioning apparatus without employing a hot water valve for shutting off hot water flowing into a heater core.
2. Description of Related Art
Conventionally, in the air-mixing type air conditioning apparatus for a vehicle, provided with a heater core (heating heat exchanger) for heating air by using hot water (engine cooling water) as heating source, generally, the maximum cooling capacity is secured by shutting off the hot water flowing into the heater core in the maximum cooling operation.
Recently, to reduce the cost of the air conditioning apparatus for a vehicle, an omission of the hot water valve has been partly put into a practice. When the hot water valve is omitted, the hot water circulates in the heater core also in the maximum cooling operation, air around the heater core is heated, and the heated air is mixed into cool air by natural convection. Thus, there occurs a problem in that the maximum cooling capacity may deteriorate.
To overcome this problem, as disclosed in JP-U-62-40013, air-mixing doors are disposed before and behind the air passage of the heater core, respectively, so that it is suppressed for the heated air to be mixed with the cool air.
However, in such a conventional type, as compared with the general type, since one of the air mixing door is added, as much the effect for reducing the cost may deteriorate.